The Absaroka difference

News that some rural Colorado counties are trying to secede from their increasingly urban and liberal state has revived talk of a historical curiosity: the attempt, during the Great Depression, to create a new state out of parts of northern Wyoming, western South Dakota and southern Montana.

I’m not concerned here with discussing the wisdom of secession, or the practicalities thereof. What got me curious today was a simpler question: what would South Dakota’s politics be like if these counties, some of the most reliably Republican in the state, weren’t part of the South Dakota electorate?

An Absaroka-less South Dakota would be more Democratic than the current Mount Rushmore state – but only to a degree.

One quick shorthand method for calculating the partisan lean of a state is the Cook Partisan Voting Index. Basically it looks at shares of the presidential vote to calculate how much more Democratic or Republican a state is than the country as a whole.

Real South Dakota (RSD), for example, has a PVI of “R+10,” meaning it’s 10 percentage points more Republican than the country. California is D+9, meaning it’s 9 percentage points more Democratic than the country. Virginia is dead even, meaning its partisan lean exactly matches the country.

Fortunately, Absaroka would have split along county boundaries, so it’s relatively easy to calculate the PVI for Alternate South Dakota. In the 2008 presidential election, John McCain would have won 52.4 percent of the two-party vote (he actually got 54.2 percent of the two-party vote). In the 2012 presidential election, Mitt Romney would have won 57.5 percent (he really won 59.2 percent). Comparing that average, 55 percent Republican, to the national Republican share of 47.1 percent, Alternate South Dakota ends up as an R+7.8.

In real life, South Dakota is R+10, so losing Absaroka would have made South Dakota about two percentage points more Democratic.

That’s not a ton. South Carolina is an R+8 state. Montana is an R+7. Both are solidly red states at the presidential level. (Georgia, at R+6, is the bluest state right now with two Republican senators.)

But small shifts can make the difference in close elections.

For example, in 2010, Kristi Noem beat Stephanie Herseth Sandlin by around 7,000 votes. But in Alternate South Dakota, without Noem’s Black Hills electoral strongholds, Herseth Sandlin narrowly wins re-election by 6,700 votes – a near inversion of the actual result. (Another potential boost for Herseth Sandlin: if Custer County were in a different state, independent B. Thomas Marking wouldn’t have been a candidate in the race.)

And Tom Daschle would have broken the Curse of Karl Mundt in 2004 if western South Dakota had gone to play in Absaroka. In real life, Thune beat Daschle by 4,500 votes. Alternate South Dakota would have voted for Daschle by a 9,300-vote margin.

(Big caveat: this is a scenario in which one assumes all other factors remain the same. In fact, a South Dakota without its western portion would have different politics. Different issues would be dominant. Candidates might take different positions, responding to different pressures from their constituents. Campaigning patterns would unfold differently.)

This only goes so far. For example, 2010 Democratic gubernatorial candidate Scott Heidepriem can draw little consolation from this counter-factual. In real life Dennis Daugaard won by 23 points and 73,000 votes. Alternate South Dakota would have voted for Daugaard by the only slightly less overwhelming total of 21 points and 52,000 votes.

What to take away? Geography matters. South Dakota is Republican through and through, and would remain so even if the most Republican part of the state were sliced off. But the slight shift toward the political center could have had big impacts in the state’s recent close elections.

Miscellaneous things I am pondering:

What would the smaller South Dakota’s nickname be? Still the Sunshine State? Or something different?

If the tourist hordes heading to the Black Hills were heading to another state, do you think Alternate South Dakota would have put tollbooths up on I-90?

Would Pierre still be the capital? The physical investment in government infrastructure would be expensive to duplicate. But while Pierre is geographically central to South Dakota and has major population centers to its west in the Black Hills, in Alternate South Dakota there’s very little to the west of Pierre.